refactor: reorganize project structure following go standards

api/playback/service_proxy.go

@@ -0,0 +1,81 @@
+package playback
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+)
+
+func (s *Service) ProxyStream(ctx context.Context, targetURL string, referer string, rangeHeader string) (int, http.Header, []byte, io.ReadCloser, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, targetURL, nil)
+	if err != nil {
+		return 0, nil, nil, nil, fmt.Errorf("invalid upstream url: %w", err)
+	}
+
+	if referer != "" {
+		req.Header.Set("Referer", referer)
+	}
+	req.Header.Set("User-Agent", defaultUserAgent)
+	if rangeHeader != "" {
+		req.Header.Set("Range", rangeHeader)
+	}
+
+	resp, err := s.httpClient.Do(req)
+	if err != nil {
+		return 0, nil, nil, nil, fmt.Errorf("upstream request failed: %w", err)
+	}
+
+	if isM3U8(targetURL, resp.Header.Get("Content-Type")) {
+		defer resp.Body.Close()
+		body, readErr := io.ReadAll(io.LimitReader(resp.Body, 2*1024*1024))
+		if readErr != nil {
+			return 0, nil, nil, nil, fmt.Errorf("read playlist failed: %w", readErr)
+		}
+
+		rewritten, rewriteErr := s.rewritePlaylistWithTokens(ctx, string(body), targetURL, referer)
+		if rewriteErr != nil {
+			return 0, nil, nil, nil, fmt.Errorf("rewrite playlist failed: %w", rewriteErr)
+		}
+
+		headers := cloneHeaders(resp.Header)
+		headers.Set("Content-Type", "application/vnd.apple.mpegurl")
+		return resp.StatusCode, headers, []byte(rewritten), nil, nil
+	}
+
+	headers := cloneHeaders(resp.Header)
+	return resp.StatusCode, headers, nil, resp.Body, nil
+}
+
+func isM3U8(targetURL string, contentType string) bool {
+	if strings.Contains(strings.ToLower(targetURL), ".m3u8") {
+		return true
+	}
+	lowerType := strings.ToLower(contentType)
+	return strings.Contains(lowerType, "application/vnd.apple.mpegurl") || strings.Contains(lowerType, "application/x-mpegurl")
+}
+
+var hopHeaders = map[string]struct{}{
+	"connection":          {},
+	"transfer-encoding":   {},
+	"keep-alive":          {},
+	"proxy-authenticate":  {},
+	"proxy-authorization": {},
+	"te":                  {},
+	"trailers":            {},
+	"upgrade":             {},
+}
+
+func cloneHeaders(src http.Header) http.Header {
+	dst := make(http.Header)
+	for key, values := range src {
+		if _, ok := hopHeaders[strings.ToLower(key)]; ok {
+			continue
+		}
+		for _, value := range values {
+			dst.Add(key, value)
+		}
+	}
+	return dst
+}